When i use " mat.maxSimultaneousLights = 20" Windows system will appear error, Mac system is normal

[Evgeni_Popov]

Here’s an explanation on why there is a limit on the number of lights you can use for a mesh at once:

Light material limit

There is a limit on the number of uniform buffers used in a shader. It seems 12 is a common value, at least it’s the one of my GPU for the vertex shader. Each light consumes a buffer. Babylon is also using a buffer for the scene, mesh and material objects. So, with 9 lights, you reach the limit of 12. Adding a new light will get you an error saying that you exceed the maximum number of uniform buffers you can use in a vertex shader. In 4.2 we did not create a uniform buffer for the mesh data, s…